Ischemic mitral regurgitation (IMR) affects 1.6 to 2.8 million Americans and increases mortality even when mild. There is a strong graded relationship between the severity of IMR and reduced survival. Valve incompetence in IMR occurs due to a variable combination of leaflet tethering and annular dilation. Mitral valve (MV) repair with undersized annuloplasty rings has become the preferred treatment; however, while annuloplasty effectively addresses annular dilatation, it does not improve and may exacerbate leaflet tethering. MV repair is associated with a 30% recurrence rate of significant IMR (e2+) within 6 months after surgery. This high recurrence rate significantly limits the efficacy of MV repair for IMR. It is likely that a standardized and reliably efficacious surgical therapeutic approach to IMR will not be achievable until the confounding phenomena of recurrent mitral regurgitation can be better understood and subsequently neutralized. A patient-specific approach to treatment, guided by preoperative imaging-based risk stratification for recurrent IMR, is apt to be the best means for achieving this important goal. It is the intent of the proposed project to develop such a tool for risk stratification. The central hypothesis of this proposal is that the degree of pre-repair mitral leaflet tethering determines the degree of recurrent mitral regurgitation after ring annuloplasty for IMR. We further hypothesize that leaflet tethering can be effectively quantified preoperatively by echocardiography and that three-dimensional echocardiography (3DE) is superior to standard two-dimensional echocardiography (2DE) for predicting the degree of recurrent IMR. The proposed study seeks to develop echocardiographic techniques to predict, preoperatively, the degree of recurrent IMR that can be expected for an individual patient within the first year after surgery. The anticipated results of the proposed study will allow surgeons to determine which IMR patients are best treated with standard MV repair (i.e. ring annuloplasty) and which are better served by valve replacement. Such an approach will limit recurrent IMR and simultaneously maximize the number of patients who realize the benefits of MV repair. Both results will improve clinical outcomes. We propose to enroll 378 patients at three high-volume cardiac surgical centers over a 5 year period. Intraoperative 2DE and 3DE parameters will be correlated with the degree of recurrent IMR at 6 and 12 months after surgery.